The present invention relates to a method for drying moist organic material, in particular for drying forage crops.
Forage crops and other moist organic materials not harvested for silage are typically dried to obtain a desired moisture level to facilitate storage over extended periods of time. Drying usually occurs naturally outdoors in the field where it is cut and sometimes crimped to aid the drying process. There are several problems with this drying method; (1) natural drying relies on atmospheric temperatures (which are low compared to what can be achieved by artificial means), (2) the relative humidity of the air (which typically varies from a low of 50% to 100% in many areas of the world), (3) movement of the air which can typically vary from 30 mile an hour winds to no wind (and even during relatively high wind conditions the air does not necessarily move rapidly at ground level), and (4) some of the crop is necessarily close to or on the ground where drying occurs slowly because of the moisture coming from below. Though not typical, several methods have been tried to dry forage crops indoors. This always involves transporting a high volume type crop that has a high moisture content thus high mass. Typically two drying methods have been used. One dries by moving atmospheric air (sometimes heated) through the hay placed over open floors until dried. Another method moves the hay through a rotating drum via very hot air blowing through that drum. The latter has achieved energy efficiencies of 1600 to 1700 BTU per pound of water removed. Again, besides the high amount of energy used, the high moisture (thus high mass) forage products need to be hauled considerable distances to achieve a reasonable level of operation for a plant that requires a substantial capital investment.
If the drying process is intended to be used in a timely and efficient connection with harvesting of the organic material, it is imperative that the drying process can be carried out in synchronization with the harvesting. There have been attempts to dry forage crops in the field after cutting such as with the use of microwave heating or squeezing moisture out of the product but all have resulted in low throughput, high energy costs, high equipment cost or loss of product value.
The present invention solves these and other problems associated with existing apparatus and methods for drying moist organic materials.